Domingo was first recruited to be a member of a secret CIA-run anti-drug operation in Colombia in Clear and Present Danger, while he was still a sergeant in the U.S. Army. He first met John Clark during this novel and has worked with him since. He has at least two advanced degrees and is fluent in English, Spanish, Russian, Japanese, and Farsi. Domingo worked with John Clark in implementing "Plan Blue" (recruitment of law enforcement officers as intelligence officers) during Executive Orders, some inside Iran. Clark and Chavez lead multiple operations for President Ryan in this novel, some inside Iran. He later was recruited into and became a team leader (with the rank of major) in the multinational counterterrorist organization RAINBOW in Rainbow Six, which defeated several terrorist groups and prevented a bioterrorism plague. It is worthy to note that he later became "Rainbow Six" himself in the later Rainbow Six video games, such as Tom Clancy's Rainbow Six: Vegas. The position was formerly held by his father-in-law, John Clark.
Domingo is known to possess at least 3 Intelligence Stars; one issued at the beginning of Debt of Honor after a successful operation in East Africa, one issued for John Clark and Domingo during the Japanese conflict, as well as one for his ongoing operations carried out in Executive Orders. These awards—generally given for valor in black operations that officially "never happened"—are awarded secretly, and no medals or ribbons are worn: their existence is classified.
Ding: "Ninja! We own the night" (proceeds to kill foe)
Enemy: (dead to quickly to respond)